The invention relates to elastomeric hose, but more particularly, the invention relates to hose with a heat cure type elastomeric tube that is cured while positioned on a mandrel that may have several bends.
Curved hose is manufactured by positioning a pre-cut length of uncured hose over a curved mandrel and then heating and curing the hose to retain a curved shape. The hose may solely comprise an elastomeric tube, or the hose may comprise an elastomeric tube surrounded by a twined reinforcement. Optionally, a cover may surround the reinforcement. Uncured elastomeric hose made from rubber has a tendency to flaten as the tube is coiled when the inside tube diameters are about one inch or greater. A partitioning agent such as mica dust is sprayed on the inside of the tube during extrusion to prevent the tube from cohering when flattened.
Lengths of uncured tube are at least partially dipped into a lubricant before they are positioned on a mandrel. The lubricant is required to slide an uncured hose over the mandrel and to remove a heat cured hose from the mandrel.
A cured hose is substantially cleaned of mica dust and lubricant before it is put in service. Residual amounts of mica dust and lubricant must be compatible with the equipment service by the hose such as an automobile cooling system.
Accordingly, the chosen lubricant must aid in sliding an uncured hose on a mandrel, it must not appreciably deteriorate as the hose is cured on the mandrel; it must aid in removing a cured hose from the mandrel; and it must be able to be substantially removed from a curved hose after curing. One lubricant that has found widespread use in curved hose making is a water soluble oil having an ethylene glycol base and sold under the Trade Name "Ucon" by Union Carbide Corporation. Most of the Ucon oil and mica dust is removed from the hose with a water solution wash. Some oil is extracted from the water solution and recovered while small residual portions are retained by the finished hose product.
While mica dust and "Ucon" oil type lubricant are acceptable processing aids to produce a satisfactory hose product, their introduction into the processing steps have several drawbacks. Both, whether introduced individually or together, must be substantially removed from a cured hose to produce a satisfactory end product. The water soluble oils have a tendency to retain oxygen molecules. When a water and combination contacts production equipment, it contributes to rapid corrosive decay of such equipment.